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PubMed1992

Purification and some properties of chlorogenic acid oxidase from apple (Malus pumila).

Chlorogenic acid oxidase was extensively purified to homogeneity from apple flesh (Malus pumila cv. Fuji). The enzyme was purified 470-fold, with a total yield close to 70% from the plastid fraction by ammonium sulfate precipitation, gel filtration and ion-exchange chromatography. The molecular weight was determined to be 65,000 by both SDS-PAGE and gel filtration chromatography. The optimum pH for the enzyme activity was around 4.0, and the enzyme was stable in the range of pH 6-8. The pI obtained by isoelectrofocusing was 5.4, and the N-terminal amino acid sequence was N-Asp-Pro-Leu-Ala-Pro-Pro-. The reaction rate of the purified enzyme was much larger for chlorogenic acid than for other o-diphenols such as (+)-catechin, (-)-epicatechin and 4-methylcatechol, and the enzyme lacked both cresolase activity and p-diphenol oxidase activity. The Km value for the enzyme was found to be 122 microM toward chlorogenic acid. The purified enzyme had far less thermal stability than the enzyme of the plastid fraction. Diethyl-dithiocarbamate, sodium azide, o-phenanthroline and sodium fluoride markedly inhibited the enzyme activity.

Amino Acid Sequence↗

PubMed1993

Electrical responses of the rat's retinal pigment epithelium to azide and thiocyanate.

In the rat under urethane anesthesia, a fast intravenous injection of a bolus of sodium azide elicited a transient cornea-positive change in transocular potential (azide response). A bolus injection of sodium thiocyanate (NaSCN) produced a cornea-negative response (SCN- response) with a similar rising phase as the azide response, but with a faster return from the peak. The peak amplitude depended on bolus volume, concentration, animal strain, and age. For more than 24 h, the azide and SCN- responses could be recorded repeatedly from a single rat with little variation in peak amplitudes. Following an administration of iodate, known to degenerate the retinal pigment epithelium (RPE), the transocular d.c. potential decreased; the azide response became smaller and then was inverted in polarity, whereas the SCN- response became larger. Azide and SCN- are assumed to depolarize and hyperpolarize the basal membrane of RPE, respectively. The equilibrium potential of ions passing through the putative azide-sensitive channels is assumed less negative than resting potential of RPE cells. The SCN- response probably represents a diffusion potential of SCN- permeating through anionic channels at a higher rate than Cl-. Results demonstrate the feasibility of in vivo electrophysiological measurement of the functional state and the structural integrity of RPE under pathological conditions.

Animals↗

PubMed1985

Homogeneous populations of Artemia nauplii and their potential use for in vitro testing in developmental toxicology.

Efforts have begun to establish test subjects other than the intact pregnant mammal to serve as models for rapid teratology screens. Artemia nauplii transcending instar I to later instars were examined to determine their potential for indicating chemicals as potential developmental hazards and thus prioritizing them for more extensive in vivo testing. Several criteria selected for assessing the system's potential for screening were the ability to: collect homogeneous populations of instar I nauplii; characterize intermediate development by technically simple measurements; and demonstrate development-related differentials in naupliar vulnerability. Homogeneous populations of nauplii were harvested from a flow-through hatching and cold storage system. Nauplii accumulated in the system are stored at 4 degrees C in a quiescent state with little physical (body length, body water volume) and biochemical (DNA and protein levels) change and thus are maintained at instar I. Intermediate development of nauplii transcending instar I to IV was characterized after the onset of 25 degrees C incubation by measuring changes in drinking activity, body length, body water volume, and DNA and protein levels. During the first day of incubation, development was greatest between 6 and 24 hours of incubation. Development-related differentials in naupliar vulnerability were shown by comparing median lethal concentrations (LC50) estimated for cadmium sulfate (CdSO4), mercuric chloride (HgCl2), and sodium azide (NaN3) at various times during incubation. With cadmium and mercury, LC50s decreased as nauplii aged and developed; whereas, with azide, LC50s did not vary. Developing nauplii were differentially vulnerable to cadmium and inorganic mercury. Artemia nauplii transcending instar I to IV appear useful for indicating chemicals that preferentially interact with developmental events.

Animals↗

PubMed1981

Effects of ionophore A23187 on calcium fluxes from cultured adrenal cells.

The effect of the calcium ionophore A23128 on calcium fluxes from Y-1 adrenal cortical cells was investigated. Conditions were chosen which are known to result in an inhibition of steroidogenesis (6 . 10(-6) M ionophore and 3 . 10(-4) M extracellular calcium). Calcium efflux from Y-1 cells exhibited two distinct phases. A fast phase which was insensitive to the mitochondrial poison sodium azide and a slow, azide-sensitive phase. The ionophore brought about a rapid increase in the rate of calcium efflux and an 84% reduction in the size of the calcium pool which was associated with the slow efflux phase as well as a reduction in its rate constant. A decrease in the size of the rapidly exchanging calcium pool was also detected. Ethanol, the solvent which was used for the ionophore, slightly increased the rate constant of the rapidly exchanging pool. Conditions which resulted in diminished steroidogenic capacity also brought about a reduction in the size of an energy dependent, intracellular pool. The data is interpreted as being consistent with a hypothesis that the ionophore-induced inhibition of steroidogenesis may be causatively related to the loss of intracellular calcium or to the mechanism which brings about the loss.

Adrenal Glands↗

PubMed1995

Assessment of biological activity and fate of organic compounds in a reactor for the measurement of biodegradable organic carbon in water.

A new, rapid method for the determination of biodegradable dissolved organic carbon (BDOC), especially suited to water industry needs, was recently proposed by the authors. This dynamic method measured the BDOC of circulating water continuously pumped over a biofilm attached to a special support (sinterized porous glass) that fills a system of two glass columns. The BDOC value corresponds to the difference in dissolved organic carbon (DOC) between inflow and outflow water samples. The analytical results are not significantly different from those of other bioassays that use indigenous bacteria, and the total duration of the analysis is less than 3 h. However, a problem common to all the BDOC methods based on attached bacteria is the extent to which the decrease in DOC during the BDOC analysis is due to true biodegradation or to adsorption of organic matter to the reactor. In the present study, a reasonable support is provided for the hypothesis that this decrease, at least in the dynamic method, is predominantly due to microbiological activity. After comparing the support (sinterized porous glass) with a good physical adsorbent (granular activated carbon), the influence of temperature, residual chlorine and sodium azide on the reactor performance was tested, and a sensitivity only attributable to biological activity was observed. Another set of experiments were performed to assess the fate and specific elimination of different organic substances, explicable assuming that biodegradation processes were involved.

Azides↗

PubMed1994

Nonenzymatic bilin addition to the alpha subunit of an apophycoerythrin.

C-Phycoerythrin is a light-harvesting protein whose alpha and beta subunits carry thioether-linked phycoerythrobilin (PEB) at cysteine residues alpha-82, alpha-139, beta-48,59 (doubly-linked), beta-80, and beta-165. The two subunits of Calothrix sp. PCC 7601 C-phycoerythrin, overexpressed together as apopolypeptides in Escherichia coli, formed inclusion bodies. Purified apo-alpha was soluble in the absence of urea, whereas the apo-beta subunit was only soluble at high urea concentrations. Products of nonenzymatic addition of PEB and phycocyanobilin (PCB) to apo-alpha were characterized by isolation of bilin peptides and spectroscopy. Reaction of PEB with the apo-alpha subunit led primarily to 15,16-dihydrobiliverdin (Cys-82) or urobilin (Cys-139) adducts, and small amounts of the natural PEB adducts at both Cys-82 and Cys-139. PCB reacted primarily with Cys-82 to form phycocyanobilin and mesobiliverdin adducts. Both PEB and PCB also formed relatively small amounts of adducts with Cys-59, which is not a bilin attachment residue in natural phycoerythrin. Sodium azide was found to promote the addition of PEB to simple thiols but not to apo-alpha phycoerythrin.

Azides↗

PubMed1988

Metabolic inhibitors and intermediate filament organization in human fibroblasts.

A number of metabolic inhibitors including the mRNA transcription inhibitor actinomycin D; the protein synthesis inhibitors emetine, cycloheximide, and puromycin; the energy metabolism inhibitors sodium azide and oligomycin; the amino acid analog L-azetidine-2-carboxylic acid; sodium fluoride; and acrylamide each cause the collapse of vimentin filament organization while leaving microtubule organization apparently unaffected in the human fibroblastic cell line MCH23. The protein kinase inhibitor N-[2-(methylamino)ethyl]-5-isoquinolinesulfonamide dihydrochloride (H8) caused a partial collapse of vimentin organization but its effect was more difficult to discern, since it also induced a dramatic change in cellular morphology. Each of these drugs produced a significant inhibition of protein synthesis at concentrations that affected vimentin organization. The mechanisms by which these drugs affect intermediate filament organization are unclear, but our results demonstrate that intermediate filament organization in MCH23 cells is affected by a wide range of drugs and that such drugs cannot be used without great caution as reagents for the study of intermediate filament organization and function.

Acrylamide↗

PubMed2003

Photobiological modulation of cell attachment via cytochrome c oxidase.

The number of cells attached to glass substrates increases if HeLa cell suspensions are irradiated with monochromatic visible-to-near infrared radiation (600-860 nm, 52 J m(-2)) prior to plating. The well-structured relationship between this biological response and the radiation wavelength (action spectrum with maxima at 620, 680, 760, and 820 nm) suggests the existence of a photoacceptor responsible for the enhancement of attachment (presumably cytochrome c oxidase, the terminal enzyme of the respiratory chain) and, secondly, the existence of signaling pathways between the mitochondria, the plasma membrane, and the nucleus of the cell. Treating the cell suspension with ouabain (a Na(+), K(+)-ATPase inhibitor), amiloride (an inhibitor of N(+)/H(+) exchangers), or sodium azide (a cytochrome c oxidase inhibitor) prior to irradiation significantly modifies the action spectrum of cell attachment enhancement. The action of the chemicals under study also depends on their concentration and radiation fluence. Our results point to the existence of at least three signaling pathways (reaction channels) relating together the cell attachment, the respiratory chain, and the Na(+), K(+)-ATPase and N(+)/H(+) exchanger activities.

Amiloride↗

PubMed2001

Nitrophenylphosphate as a tool to characterize gill Na(+), K(+)-ATPase activity in hyperregulating Crustacea.

The kinetic properties of a gill Na(+), K(+)-ATPase from the freshwater shrimp Macrobrachium olfersii were studied using p-nitrophenylphosphate (PNPP) as a substrate. Sucrose gradient centrifugation of the microsomal fraction revealed a single protein fraction that hydrolyzed PNPP. The Na(+), K(+)-ATPase hydrolyzed PNPP (K(+)-phosphatase activity) obeying Michaelis-Menten kinetics with K(M)=1.72+/-0.06 mmol l(-1) and V(max)=259.1+/-11.6 U mg(-1). ATP was a competitive inhibitor of K(+)-phosphatase activity with a K(i)=50.1+/-2.5 micromol l(-1). A cooperative effect for the stimulation of the enzyme by potassium (K(0.5)=3.62+/-0.18 mmol l(-1); n(H)=1.5) and magnesium ions (K(0.5)=0.61+/-0.02 mmol l(-1), n(H)=1.3) was found. Sodium ions had no effect on K(+)-phosphatase activity up to 1.0 mmol l(-1), but above 80 mmol l(-1) inhibited the original activity by approximately 75%. In the range of 0-10 mmol l(-1), sodium ions did not affect stimulation of the K(+)-phosphatase activity by potassium ions. Ouabain (K(i)=762.4+/-26.7 micromol l(-1)) and orthovanadate (K(i)=0.25+/-0.01 micromol l(-1)) completely inhibited the K(+)-phosphatase activity, while thapsigargin, oligomycin, sodium azide and bafilomycin were without effect. These data demonstrate that the activity measured corresponds to that of the K(+)-phosphatase activity of the Na(+), K(+)-ATPase alone and suggest that the use of PNPP as a substrate to characterize K(+)-phosphatase activity may be a useful technique in comparative osmoregulatory studies of Na(+), K(+)-ATPase activities in crustacean gill tissues, and for consistent comparisons with well known mechanistic properties of the vertebrate enzyme.

Adenosine Triphosphate↗

PubMed2003

Factors affecting the microclimate pH of the rat jejunum in ringer bicarbonate buffer.

General characteristics of the microclimate layer on the mucosal surface of the rat jejunum incubated in bicarbonate buffers were investigated in vitro using pH sensitive flat membrane microelectrode. Jejunal surface microclimate (JSM) pH changed from 7.30+/-0.03 to 5.83+/-0.04 when the incubation buffer pH decreased from 8.03+/-0.02 to 6.12+/-0.01. Treatment of the mucosal side with mucolytic substances L-cysteine (1% (wt/v)) and 1,4-dithio-DL-threitol (2 mM) significantly (p<0.01) increased JSM pH. Respiratory chain inhibitor, sodium azide (10 mM) also significantly (p<0.05) increased JSM pH. D-Glucose (10 mM) at the mucosal side markedly (p<0.05) decreased JSM pH, which was attenuated by Na(+)/H(+) exchange inhibitor, amiloride (1 mM). Amiloride had no effect on JSM pH when D-glucose was not present at the mucosal side. In contrast to previous observations using bicarbonate free incubation buffers, we have demonstrated that JSM pH is not a constant value, but is dependent on pH of the incubation buffer. Additionally, Na(+)/H(+) exchanger does not contribute to acidic properties of JSM, when there is no D-glucose in the bicarbonate incubation buffer at the mucosal side of the tissue. In conclusion, we suggest that the bicarbonate buffers which are more close to in vivo situation than bicarbonate free buffers should be preferable incubation media when examining JSM.

Amiloride↗

PubMed1990

Quantitation of hydrogen peroxide formed during UV-visible irradiation of protoporphyrin, coproporphyrin and uroporphyrin.

Free porphyrins are strong photosensitizers. Previously reported findings indicate that the in vitro cell lysis induced by irradiation in the presence of coproporphyrin (CP) and uroporphyrin (UP) is mediated by H2O2 and that induced by irradiation with protoporphyrin (PP) is not mediated by H2O2. In the present study the possible role of H2O2 in the porphyrin photosensitization was investigated by direct measurement of the H2O2 formed during the irradiation of PP, CP and UP. Our results show that the amount of H2O2 formed decreased in the following order: UP, CP, PP. The amounts of H2O2 formed during irradiation of CP and PP were approximately 86% and 38% respectively in comparison to the H2O2 formed during the irradiation of UP. The formation of H2O2 was inhibited by sodium azide, a strong quencher of singlet oxygen. These observations are in good agreement with the previous report that the in vitro photolysis of Ehrlich ascites carcinoma cells by UP and CP, but not that by PP, was inhibited by catalase and clinical findings with patients with erythropoietic protoporphyria (EPP) and porphyria cutanea tarda (PCT). The patients with EPP, where the photosensitivity is due to PP, respond well to beta-carotene while beta-carotene does not protect against the photosensitivity in PCT, in which case the photosensitivity is due to uroporphyrin.

Azides↗

PubMed1990

Interrelation between nucleotide degradation and aldehyde formation in red blood cells. Influence of xanthine oxidase on metabolism: an application of nucleotide and aldehyde analyses by high-performance liquid chromatography.

The mechanism by which hypoxia leads to irreversible cellular damage is poorly understood. A decrease in purine nucleotides is common to all ischaemic tissues, yielding hypoxanthine as the substrate of the xanthine oxidase reaction. Excessive production of radicals via xanthine oxidase induces peroxidation of unsaturated fatty acids, accompanied with the formation of aldehydes. The nucleotides and aldehydes were determined by high-performance liquid chromatography (HPLC) of red blood cell extracts. Nucleotides and their derivatives were determined by HPLC on an ODS column and elution with 10 mM phosphate buffer containing 2 mM tert.-butylammonium phosphate. The aldehyde production in glucose deprived red blood cells was stimulated by addition of xanthine oxidase and by inhibition of different haemotype enzymes with sodium azide. Aldehydes were analysed by derivatization to dinitrophenylhydrazones, followed by thin-layer chromatographic and HPLC separation with aqueous methanol on an ODS column. The HPLC methods presented are appropriate for the determination of nucleotides, nucleosides and nucleobases, in addition to alkenals and hydroxyalkenals in extracts of oxidatively stressed red blood cells.

Aldehydes↗

PubMed2001

Adsorption of hydrazoic acid from aqueous solution by macroreticular resin.

Sodium azide is a key component in the automobile air bag. When dissolved in aqueous solution, it reacts rapidly with water to form hydrazoic acid which is a highly toxic chemical and is strongly regulated by government. In the present study, adsorption of hydrazoic acid from aqueous solution by macroreticular resin is investigated. This method can provides a convenient means for dealing with the toxic hydrazoic acid. Experimental tests of batch equilibrium adsorption and continuous column adsorption of hydrazoic acid were conducted and the test results were employed to establish adsorption isotherm and to evaluate the column adsorption efficiency. The test results revealed that the multilayer adsorption isotherms, like the modified Langmuir or Jossens model, are needed to adequately describe the hydrazoic acid adsorption equilibrium between the liquid and solid (resin) phases. In the column adsorption process, a theoretical model was adopted for representing the hydrazoic acid change in the aqueous solution exiting the column and the verified theoretical model significantly facilitates prediction of adsorption breakthroughs and column design. Regeneration of exhausted resin was investigated. Solution of 10% (w/w) NaCl was found to be a very efficient regenerant.

Adsorption↗

PubMed1990

Tetraethylammonium transport by OK cells.

Mechanisms exist in renal proximal tubules for the mediated transepithelial secretion or reabsorption of endogenous and exogenous organic cations. In the studies presented here, the uptake of the organic cation tetraethylammonium (TEA) into confluent monolayers of opossum kidney cells was evaluated to determine if these cells might serve as an in vitro model of this transport pathway. 3H-TEA entered opossum kidney cells in a time-dependent manner. Uptake at early time points was saturable with an apparent Km of 59.1 +/- 11.2 microM and a Vmax of 1,292 +/- 210 fmol/micrograms of DNA. TEA uptake was inhibited in a dose-dependent manner by several other organic cations including amiloride, cimetidine, verapamil, procainamide, quinidine and N1-methylnicotinamide. With 1 mM concentrations of these compounds, uptake was virtually eliminated. However, another organic cation, N'-methylnicotinamide caused only minimal inhibition. TEA uptake was significantly reduced by sodium azide, suggesting dependence on oxidative phosphorylation. An alkaline medium pH enhanced TEA uptake, but, at the same pH, uptake was similar in the presence or absence of bicarbonate. When cellular pH was altered by ammonium chloride addition or removal, TEA uptake was not affected. Thus, organic cation/proton exchange, as has been demonstrated previously in apical membrane vesicles prepared from proximal tubules, is evidently not responsible for TEA uptake. Similarly, uptake does not appear to result from organic cation/organic cation exchange. These results indicate that the plasma membrane of opossum kidney cells contains a transport system(s) for the mediated uptake of organic cations and that these cells may be a useful mode for further study of renal epithelial transport of these solutes.

Animals↗

PubMed1981

Iron absorption in the everted chicken intestine.

Everted chicken intestines from 2-4 week old males were prepared according to the Wilson and Wiseman technique. The sacs were kept in a glucose ionic balanced solution, containing different cold iron concentrations (0.02; 0.01; 0.5; 1 mM Fe) and 59Fe was added as a tracer. The mucosal iron uptake and the iron transfer in the serosal fluid were determined at different intervals (1; 5; 10; 20 min) and in three main segments. The viability of the intestinal sacs was controlled by manometric O2 evaluation. The iron mucosal uptake was proportional to the iron concentration but the serosal iron transfer presented a saturation level, with similar behavior for both the duodenum and the jejunum. Iron transfer decreased with time and this could suggest a serosal to mucosal reflux. No effect was noted from the presence of metabolic inhibitors (0.01 mM sodium azide or 0.5-2 mM 2-4-dinitrophenol).

Animals↗

PubMed1991

Azide determination in protein samples by ion chromatography.

Sodium azide is used as an anti-fungal agent in protein samples in the health related scientific community. Due to its toxic nature, monitoring of the azide level in proteins used in scientific research is necessary. Ion-exchange chromatography has been used to quantitate azide levels in protein samples. Anion-exchange methodology is described which allows for the separation of azide from various common anions found in analytical grade protein sample matrices. The analytical system described utilizes a polymer [poly(styrene-divinylbenzene)] stationary phase which has been surface sulfonated followed by the binding of the aminated latex bead active ion-exchange sites (Dionex, AS4A column). Sodium tetraborate is used as the weak anion-exchange mobile phase. A vendor ion-exchange column comparison is made along with eluent composition and selection studies. Method validation data are presented including: calibration plots for external standardization, limit of detection and method recovery. Various types of proteins are assayed using the described method.

Azides↗

PubMed2004

Effects of airbag deployment: lesions, epidemiology, and management.

Airbags are restraining safety devices, but their activation may sometimes induce injuries during road accidents. Rapid deceleration due to an impact causes the ignition of a sodium azide cartridge, which releases nitrogen gas to inflate the nylon rubber bag. Numerous high-temperature gases, sodium hydroxide, carbon dioxide, and various other metallic oxides are also released producing a corrosive alkaline aerosol. Cutaneous and extracutaneous injuries due to airbag deployment may occur. Cutaneous injuries are frequent, and consist of irritant dermatitis, and chemical and thermal burns. Furthermore, numerous kinds of traumatic lesions (abrasions, friction burns, and lacerations) may be observed. Extracutaneous damage may involve the eyes, ears, cardiovascular system, nerves, joints, and bones. The nature of airbag lesions, their frequency, and management are reported. Even though the majority of airbag lesions are minor and do not require hospitalization, correct diagnosis and the choice of the most suitable treatment are necessary.

Accidents, Traffic↗

PubMed1985

Influence of endogenous catalase activity on the sensitivity of the oral bacterium Actinobacillus actinomycetemcomitans and the oral haemophili to the bactericidal properties of hydrogen peroxide.

Actinobacillus actinomycetemcomitans and the genetically-related oral haemophili (Haemophilus segnis, Haemophilus aprhophilus and Haemophilus paraphrophilus) exhibit a range of sensitivities to the lethal effect of hydrogen peroxide (H2O2), A. actinomycetemcomitans being the most resistant. To extend this information, susceptibility to a range of H2O2 concentrations (10(-6)-10(-3) M) was assessed by incubating bacterial suspensions for 1 h at 37 degrees C in the presence of H2O2 and spreading the suspensions on chocolate agar plates to determine the concentration of H2O2 producing a 50 per cent reduction in colony-forming units (LD50). Catalase activity was quantified with a Clark-type oxygen electrode, which polarographically monitored the formation of dissolved oxygen in bacterial suspensions or sonicates following addition of reagent H2O2. Sensitivity to H2O2 did not correlate with catalase activity, either in intact cells or in bacterial sonicates. Specifically, some bacterial strains with undetectable catalase activity were highly resistant to H2O2. Micromolar concentrations of sodium azide which completely inhibited cell-associated catalase activity did not affect the resistance of A. actinomycetemcomitans to H2O2. Thus, the endogenous catalase activity of A. actinomycetemcomitans and certain oral haemophili is not an important determinant of resistance to the bactericidal effects of H2O2.

Actinobacillus↗